No, the 99% is the android compatibility.
Because sailfishos is not a Google certified platform, every app that uses root detection or play integrity check, won't run.
And which apps use those checks? Not the freemium games. Those are designed to maximize ad viewing, so they want to block uncertified devices
Also: an average freemium game can adapt the UI on a 480*640 screen (big buttons), while almost no developer tests normal UI in such a low resolution. And nobody tests movement of input focus with keypad. Chances of a broken UI that can't be interacted with the t9 keypad are very high.
This is why they showed WhatsApp, Spotify (two commercial apps that are tested and working on the lowest end devices with tiny screens like the qin phones) and AntennaPod (which being open source they can send a PR to fix UI issues) and dismissed the rest as "we block all the useless stuff"
So what I mean is, the phone can run 99% of android apps on the play store using aurora, but, because the play store has million of useless/slip/shovelware games, if you really need to run a specific app for work or for banking, chances is the app is in the 1% incompatible range and not the 99%